Lidar systems for near-field and far-field detection, and related methods and apparatus

ABSTRACT

A light detection and ranging (LiDAR) method may include generating, by a first transmitter, a first light illumination signal; generating, by a second transmitter, a second light illumination signal; receiving first return signals corresponding to the first light illumination signal; receiving second return signals corresponding to the second light illumination signal; and sampling the first return signals or the second return signals during a short-range sampling period, such that the short-range sampling period avoids a period of dazzle.

FIELD OF TECHNOLOGY

The present disclosure relates generally to light detection and ranging(“LiDAR”) technology and, more specifically, to LiDAR systems fordetecting objects in both the near and far fields.

BACKGROUND

Light detection and ranging (“LiDAR”) systems measure the attributes oftheir surrounding environments (e.g., shape of a target, contour of atarget, distance to a target, etc.) by illuminating the target withpulsed laser light and measuring the reflected pulses with sensors.Differences in laser return times and wavelengths can then be used tomake digital, three-dimensional (“3D”) representations of a surroundingenvironment. LiDAR technology may be used in various applicationsincluding autonomous vehicles, advanced driver assistance systems,mapping, security, surveying, robotics, geology and soil science,agriculture, unmanned aerial vehicles, airborne obstacle detection(e.g., obstacle detection systems for aircraft), and so forth. Dependingon the application and associated field of view (FOV), multiple channelsor laser beams may be used to produce images in a desired resolution. ALiDAR system with greater numbers of channels can generally generatelarger numbers of pixels.

In a conventional multi-channel LiDAR device, optical transmitters arepaired with optical receivers to form multiple “channels.” In operation,each channel's transmitter emits an optical (e.g., laser) illuminationsignal into the device's environment and each channel's receiver detectsthe portion of the return signal that is reflected back to the receiverby the surrounding environment. In this way, each channel provides“point” measurements of the environment, which can be aggregated withthe point measurements provided by the other channel(s) to form a “pointcloud” of measurements of the environment.

Advantageously, the measurements collected by any LiDAR channel may beused, inter alia, to determine the distance (i.e., “range”) from thedevice to the surface in the environment that reflected the channel'stransmitted optical signal back to the channel's receiver. The range toa surface may be determined based on the time of flight (TOF) of thechannel's signal (e.g., the time elapsed from the transmitter's emissionof the optical (e.g., illumination) signal to the receiver's receptionof the return signal reflected by the surface).

In some instances, LiDAR measurements may also be used to determine thereflectance of the surface that reflects an optical (e.g., illumination)signal. The reflectance of a surface may be determined based on theintensity on the return signal, which generally depends not only on thereflectance of the surface but also on the range to the surface, theemitted signal's glancing angle with respect to the surface, the powerlevel of the channel's transmitter, the alignment of the channel'stransmitter and receiver, and other factors.

SUMMARY

Disclosed herein are LiDAR systems for near-field and far-fielddetection, and related methods and apparatus. In a first aspect, a lightdetection and ranging (LiDAR) method for near-field detection includesgenerating, by a first transmitter, a first light illumination signal;generating, by a second transmitter, a second light illumination signal;receiving first return signals corresponding to the first lightillumination signal; receiving second return signals corresponding tothe second light illumination signal; and sampling the first returnsignals or the second return signals during a short-range samplingperiod, such that the short-range sampling period avoids a period ofdazzle. In some applications, the short-range sampling period occursbefore the dazzle signal is received, whereas, in other applications,the short-range sampling period occurs after a last return of the firstreturn signals. Advantageously, each of the first return signal and thesecond return signal may be received by a common channel signaldetector. Optionally, the method may also include diffusing, using adiffuser, at least one of the first light signal and the second lightsignal.

In a second aspect, a light detection and ranging (LiDAR) systemincludes a first transmitter, a second transmitter, and a receiver. Insome embodiments, the first transmitter is adapted to generate and emita first light illumination signal towards a medium-range scan areaand/or a long-range scan area, and the receiver is adapted to detect andreceive first return signals corresponding to the first lightillumination signal; the second transmitter is adapted to generate andemit a second light illumination signal towards at least one object in ashort-range scan area within a near field, wherein the receiver isfurther adapted to receive second return signals corresponding to thesecond light illumination signal.

The above and other preferred features, including various novel detailsof implementation and combination of events, will now be moreparticularly described with reference to the accompanying figures andpointed out in the claims. It will be understood that the particularsystems and methods described herein are shown by way of illustrationonly and not as limitations. As will be understood by those skilled inthe art, the principles and features described herein may be employed invarious and numerous embodiments without departing from the scope of anyof the present inventions. As can be appreciated from foregoing andfollowing description, each and every feature described herein, and eachand every combination of two or more such features, is included withinthe scope of the present disclosure provided that the features includedin such a combination are not mutually inconsistent. In addition, anyfeature or combination of features may be specifically excluded from anyembodiment of any of the present inventions.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures, which are included as part of the presentspecification, illustrate the presently preferred embodiments andtogether with the general description given above and the detaileddescription of the preferred embodiments given below serve to explainand teach the principles described herein.

FIG. 1 shows an illustration of an exemplary LiDAR system, in accordancewith some embodiments.

FIG. 2A shows an illustration of the operation of the LiDAR system ofFIG. 1, in accordance with some embodiments.

FIG. 2B shows an illustration of optical components of a channel of aLiDAR system, in accordance with some embodiments.

FIG. 3A shows a block diagram of a hybrid LiDAR system, in accordancewith some embodiments.

FIG. 3B shows a cross-sectional view of a portion of a hybrid LiDARsystem, in accordance with some embodiments.

FIG. 3C shows a cross-sectional view of a short-range LiDAR transmitter,in accordance with some embodiments.

FIG. 4 shows a block diagram of a computing device/information handlingsystem, in accordance with some embodiments.

FIG. 5 shows a flow chart of a method of avoiding dazzle to detect(e.g., short-range) return signals of objects in a near field, inaccordance with some embodiments.

FIGS. 6A and 6B show illustrative examples of received return signalsduring a short-range sampling period occurring before dazzle occurs, inaccordance with some embodiments.

FIGS. 7A and 7B show illustrative examples of received return signalsduring a short-range sampling period occurring after receipt of the last(e.g., long-range) return signals, in accordance with some embodiments.

FIG. 8 shows the relationship between dazzle and received (e.g.,imaging) signals in accordance with the prior art.

While the present disclosure is subject to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and will herein be described in detail. Thepresent disclosure should not be understood to be limited to theparticular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the present disclosure.

DETAILED DESCRIPTION

Systems and methods for LiDAR-based near-field and far-field detectionare disclosed. It will be appreciated that, for simplicity and clarityof illustration, where considered appropriate, reference numerals may berepeated among the figures to indicate corresponding or analogouselements. In addition, numerous specific details are set forth in orderto provide a thorough understanding of the exemplary embodimentsdescribed herein. However, it will be understood by those of ordinaryskill in the art that the exemplary embodiments described herein may bepracticed without these specific details.

Motivation for and Benefits of Some Embodiments

Problematically, conventional LiDAR devices that are capable of medium-to long-range detection of objects in the far field are not capable ofhigh-quality short-range detection of objects in the near field.Furthermore, during a brief time period occurring shortly after aconventional LiDAR device transmits the ranging (e.g., illumination)signal, the LiDAR detector may be blinded by “dazzle.” Dazzle refers toa phenomenon whereby the channel receiver detects (and is blinded by)portions of the transmitted ranging (e.g., illumination) signal thathave not been reflected by objects external to the LiDAR device. In someinstances, dazzle may be caused by one or more of: leakage of thetransmitted ranging signal within or between channels, partialreflection of the transmitted signals by the window, blockage on thewindow through which the ranging (e.g., illumination) signals are meantto be transmitted, back reflection of the ranging (e.g., illumination)signals by a lens or other optical device, and the like.Disadvantageously, conventional LiDAR devices are unable to discernreturn signals reflected back to the channel receivers from short-rangeobjects located in the near field (e.g., objects within a few meters(1-2 meters)) due to the presence of dazzle.

Referring to FIG. 8, the relationship between the received dazzle 20 anda return signal 25 reflected by an object in the near field is shown.Disadvantageously, the dazzle 20 typically occurs concurrently asshorter-range return signals arrive at the LiDAR detectors, essentiallyblinding them, preventing the LiDAR detectors from detecting the returnsignals.

Accordingly, it would be desirable to provide a (e.g., solid-state)LiDAR system that is structured and arranged to provide short-rangedetection of objects in the near field and, moreover to provide short-,medium-, and long-range detection data concurrently.

Terminology

Measurements, sizes, amounts, and the like may be presented herein in arange format. The description in range format is provided merely forconvenience and brevity and should not be construed as an inflexiblelimitation on the scope of the invention. Accordingly, the descriptionof a range should be considered to have specifically disclosed all thepossible subranges as well as individual numerical values within thatrange. For example, description of a range such as 1-20 meters should beconsidered to have specifically disclosed subranges such as 1 meter, 2meters, 1-2 meters, less than 2 meters, 10-11 meters, 10-12 meters,10-13 meters, 10-14 meters, 11-12 meters, 11-13 meters, etc.

Furthermore, connections between components or systems within thefigures are not intended to be limited to direct connections. Rather,data or signals between these components may be modified, re-formatted,or otherwise changed by intermediary components. Also, additional orfewer connections may be used. The terms “coupled,” “connected,” or“communicatively coupled” shall be understood to include directconnections, indirect connections through one or more intermediarydevices, wireless connections, and so forth.

Reference in the specification to “one embodiment,” “preferredembodiment,” “an embodiment,” “some embodiments,” or “embodiments” meansthat a particular feature, structure, characteristic, or functiondescribed in connection with the embodiment is included in at least oneembodiment of the invention and may be in more than one embodiment.Also, the appearance of the above-noted phrases in various places in thespecification is not necessarily referring to the same embodiment orembodiments.

The use of certain terms in various places in the specification is forillustration purposes only and should not be construed as limiting. Aservice, function, or resource is not limited to a single service,function, or resource; usage of these terms may refer to a grouping ofrelated services, functions, or resources, which may be distributed oraggregated.

Furthermore, one skilled in the art shall recognize that: (1) certainsteps may optionally be performed; (2) steps may not be limited to thespecific order set forth herein; (3) certain steps may be performed indifferent orders; and (4) certain steps may be performed simultaneouslyor concurrently.

The term “approximately”, the phrase “approximately equal to”, and othersimilar phrases, as used in the specification and the claims (e.g., “Xhas a value of approximately Y” or “X is approximately equal to Y”),should be understood to mean that one value (X) is within apredetermined range of another value (Y). The predetermined range may beplus or minus 20%, 10%, 5%, 3%, 1%, 0.1%, or less than 0.1%, unlessotherwise indicated.

The indefinite articles “a” and “an,” as used in the specification andin the claims, unless clearly indicated to the contrary, should beunderstood to mean “at least one.” The phrase “and/or,” as used in thespecification and in the claims, should be understood to mean “either orboth” of the elements so conjoined, i.e., elements that areconjunctively present in some cases and disjunctively present in othercases. Multiple elements listed with “and/or” should be construed in thesame fashion, i.e., “one or more” of the elements so conjoined. Otherelements may optionally be present other than the elements specificallyidentified by the “and/or” clause, whether related or unrelated to thoseelements specifically identified. Thus, as a non-limiting example, areference to “A and/or B”, when used in conjunction with open-endedlanguage such as “comprising” can refer, in one embodiment, to A only(optionally including elements other than B); in another embodiment, toB only (optionally including elements other than A); in yet anotherembodiment, to both A and B (optionally including other elements).

As used in the specification and in the claims, “or” should beunderstood to have the same meaning as “and/or” as defined above. Forexample, when separating items in a list, “or” or “and/or” shall beinterpreted as being inclusive, i.e., the inclusion of at least one, butalso including more than one, of a number or list of elements, and,optionally, additional unlisted items. Only terms clearly indicated tothe contrary, such as “only one of” or “exactly one of,” or, when usedin the claims, “consisting of,” will refer to the inclusion of exactlyone element of a number or list of elements. In general, the term “or”as used shall only be interpreted as indicating exclusive alternatives(i.e. “one or the other but not both”) when preceded by terms ofexclusivity, such as “either,” “one of,” “only one of,” or “exactly oneof.” “Consisting essentially of,” when used in the claims, shall haveits ordinary meaning as used in the field of patent law.

As used in the specification and in the claims, the phrase “at leastone,” in reference to a list of one or more elements, should beunderstood to mean at least one element selected from any one or more ofthe elements in the list of elements, but not necessarily including atleast one of each and every element specifically listed within the listof elements and not excluding any combinations of elements in the listof elements. This definition also allows that elements may optionally bepresent other than the elements specifically identified within the listof elements to which the phrase “at least one” refers, whether relatedor unrelated to those elements specifically identified. Thus, as anon-limiting example, “at least one of A and B” (or, equivalently, “atleast one of A or B,” or, equivalently “at least one of A and/or B”) canrefer, in one embodiment, to at least one, optionally including morethan one, A, with no B present (and optionally including elements otherthan B); in another embodiment, to at least one, optionally includingmore than one, B, with no A present (and optionally including elementsother than A); in yet another embodiment, to at least one, optionallyincluding more than one, A, and at least one, optionally including morethan one, B (and optionally including other elements).

The use of “including,” “comprising,” “having,” “containing,”“involving,” and variations thereof, is meant to encompass the itemslisted thereafter and additional items.

Use of ordinal terms such as “first,” “second,” “third,” etc., in theclaims to modify a claim element does not by itself connote anypriority, precedence, or order of one claim element over another or thetemporal order in which acts of a method are performed. Ordinal termsare used merely as labels to distinguish one claim element having acertain name from another element having a same name (but for use of theordinal term), to distinguish the claim elements.

Exemplary LiDAR Systems

A light detection and ranging (“LiDAR”) system may be used to measurethe shape and contour of the environment surrounding the system. LiDARsystems may be applied to numerous applications including autonomousnavigation and aerial mapping of surfaces. In general, a LiDAR systememits (e.g., illumination) light (e.g., laser) pulses that aresubsequently reflected by objects within the environment in which thesystem operates. The time each pulse travels from being emitted to beingreceived (i.e., time-of-flight) may be measured to determine thedistance between the LiDAR system and the object that reflects thepulse. The science of LiDAR systems is based on the physics of light andoptics.

In a LiDAR system, (e.g., illumination) light may be emitted from arapidly firing laser. Laser (e.g., illumination) light travels through amedium and reflects off points of surfaces in the environment (e.g.,surfaces of buildings, tree branches, vehicles, etc.). The reflectedlight energy returns to a LiDAR detector where it may be recorded andused to map the environment.

FIG. 1 depicts the operation of the medium- and long-range portion of anexemplary LiDAR system 100, according to some embodiments. In theexample of FIG. 1, the LiDAR system 100 includes a LiDAR device 102,which may include a transmitter 104 that is configured to generate andtransmit an emitted (e.g., illumination) light signal 110, a receiver106 that is configured to detect a return light signal 114, and acontrol & data acquisition module 108. The transmitter 104 may include alight source (e.g., laser), electrical components operable to activate(“drive”) and deactivate the light source in response to electricalcontrol signals, and optical components adapted to shape and redirectthe light emitted by the light source. The receiver 106 may include anoptical detector (e.g., photodiode) and optical components adapted toshape return light signals 114 and direct those signals to the detector.In some implementations, one or more of optical components (e.g.,lenses, mirrors, etc.) may be shared by the transmitter and thereceiver. The LiDAR device 102 may be referred to as a LiDAR transceiveror “channel.” In operation, the emitted (e.g., illumination) lightsignal 110 propagates through a medium and reflects off an object(s)112, whereby a return light signal 114 propagates through the medium andis received by receiver 106.

The control & data acquisition module 108 may be adapted to control thelight emission by the transmitter 104 and may record data derived fromthe return light signal 114 detected by the receiver 106. In someembodiments, the control & data acquisition module 108 is furtheradapted to control the power level at which the transmitter 104 operateswhen emitting (e.g., illumination) light. For example, the transmitter104 may be configured to operate at a plurality of different powerlevels, and the control & data acquisition module 108 may select thepower level at which the transmitter 104 operates at any given time. Anysuitable technique may be used to control the power level at which thetransmitter 104 operates. In some variations, the control & dataacquisition module 108 may be adapted to determine (e.g., measure)particular characteristics of the return light signal 114 detected bythe receiver 106. For example, the control & data acquisition module 108may be configured to measure the intensity of the return light signal114 using any suitable technique.

A LiDAR transceiver 102 may include one or more optical lenses and/ormirrors (not shown) to transmit and shape the emitted (e.g.,illumination) light signal 110 and/or to redirect and shape the returnlight signal 114. For example, the transmitter 104 may emit a laser beamhaving a plurality of pulses in a particular sequence. Design elementsof the receiver 106 may include its horizontal field of view(hereinafter, “FOX”) and its vertical FOV. One skilled in the art willrecognize that the FOV parameters effectively define the visibilityregion relating to the specific LiDAR transceiver 102. More generally,the horizontal and vertical FOVs of a LiDAR system 100 may be defined bya single LiDAR device (e.g., sensor) or may relate to a plurality ofconfigurable sensors (which may be exclusively LiDAR sensors or may havedifferent types of sensors). The FOV may be considered a scanning areafor a LiDAR system 100. A scanning mirror may be utilized to obtain ascanned FOV.

In some implementations, the LiDAR system 100 may also include or may beelectronically coupled to a data analysis & interpretation module 109,which may be adapted to receive output (e.g., via connection 116) fromthe control & data acquisition module 108 and, moreover, to perform dataanalysis functions on, for example, return signal data. The connection116 may be implemented using a wireless or non-contact communicationtechnique.

FIG. 2A illustrates the operation of the medium- and long-rangeportion(s) of a LiDAR system 202, in accordance with some embodiments.In the example of FIG. 2A, two return light signals 203 and 205 areshown, corresponding to medium-range and long-range return signals.Laser beams generally tend to diverge as they travel through a medium.Due to the laser's beam divergence, a single (e.g., illumination) laseremission may hit multiple objects at different ranges from the LiDARsystem 202, producing multiple return signals 203, 205. The LiDAR system202 may analyze multiple return signals 203, 205 and report one of thereturn signals (e.g., the strongest return signal, the last returnsignal, etc.) 203, 205 or more than one (e.g., all) of the returnsignals 203, 205. In the illustrative example shown in FIG. 2A, LiDARsystem 202 emits a (e.g., illumination) laser in the direction ofmedium-range wall 204 and long-range wall 208. As illustrated, themajority of the emitted (e.g., illumination) beam hits the medium-rangewall 204 at area 206 resulting in a (e.g., medium-range) return signal203, and another portion of the emitted (e.g., illumination) beam hitsthe long-range wall 208 at area 210 resulting in a (e.g., long-range)return signal 205. Return (e.g., medium-range) signal 203 may have ashorter TOF and a stronger received signal strength compared with return(e.g., long-range) signal 205. In both single- and multiple-return LiDARsystems 202, it is important that each return signal 203, 205 isaccurately associated with the transmitted (e.g., illumination) lightsignal so that an accurate TOF may be calculated.

Some embodiments of a LiDAR system may capture distance data in a (e.g.,single plane) two-dimensional (2D) point cloud manner. These LiDARsystems may be used in industrial applications, or for surveying,mapping, autonomous navigation, and other uses. Some embodiments ofthese systems rely on the use of a single laser emitter/detector paircombined with a moving mirror to effect scanning across at least oneplane. This mirror may reflect the emitted (e.g., illumination) lightfrom the transmitter (e.g., laser diode), and/or may reflect the returnlight to the detector. Use of a movable (e.g., oscillating) mirror inthis manner may enable the LiDAR system to achieve 90-180-360 degrees ofazimuth (horizontal) view while simplifying both the system design andmanufacturability. Many applications require more data than just asingle (e.g., 2D) plane. The 2D point cloud, however, may be expanded toform a 3D point cloud, in which multiple 2D point clouds are used, eachpointing at a different elevation (i.e., vertical) angle. Designelements of the receiver of the LiDAR system 202 may include thehorizontal FOV and the vertical FOV.

FIG. 2B depicts a set of optical components 250 of a channel 102 of aLiDAR system 100 according to some embodiments. In the example of FIG.2B, the LiDAR channel 102 uses a single emitter 252/detector 262 paircombined with a fixed mirror 254 and a movable mirror 256 to effectivelyscan across a plane. Distance measurements obtained by such a system maybe effectively two-dimensional (e.g., planar), and the captured distancepoints may be rendered as a 2D (e.g., single plane) point cloud. In someembodiments, but without limitation, the movable mirror 256 mayoscillate at very fast speeds (e.g., thousands of cycles per minute).

The emitted laser signal 251 may be directed to a fixed mirror 254,which may reflect the emitted laser signal 251 to the movable mirror256. As movable mirror 256 moves (e.g., oscillates), the emitted lasersignal 251 may reflect off an object 258 in its propagation path. Thereflected return signal 253 may be coupled to the detector 262 via themovable mirror 256 and the fixed mirror 254. Design elements of theLiDAR system 250 include the horizontal FOV and the vertical FOV, whichdefine a scanning area.

Hybrid LiDAR System

Referring to FIG. 3A, a block diagram of an illustrative (e.g., hybrid)LiDAR system 300 that is structured and arranged to provide long-,medium-, and short-range detection in accordance with some embodimentsis shown. Although the hybrid LiDAR system 300 will be described as partof a system that is capable of detecting and processing short-rangereturn signals as well as medium- and long-range return signals, thoseskilled in the art can appreciate that a stand-alone system may bedesigned to detect and process only short-range return signals. In someimplementations, the short-range components are capable of detectingobjects in the range of about 10 to about 20 meters from the LiDARsystem 300; although application of a diffuser 306 to the short-rangeillumination signals may limit the detection range to about 1 or 2meters (or less).

In some variations, the hybrid LiDAR system 300 is a solid-state systemthat is structured and arranged to include a far-field transmitter 104(e.g., “first,” “primary,” or “far-field” transmitter), a transmitter304 (e.g., “second,” “supplemental,” “flash,” or “near-field”transmitter), a receiver 106, a control & data acquisition module 108,and a data analysis & interpretation module 109. Collectively, thefar-field transmitter 104, receiver 106, and control & data acquisitionmodule 108 may be configured to operate as a far-field LiDAR device(e.g., channel), capable of providing data from medium- and long-rangescan areas as previously described. In some implementations, thefar-field transmitter 104 is configured to emit laser (e.g.,illumination) light signals 110 towards a medium- and long-range scanarea and to receive return signals 114 therefrom. In some embodiments,the light source of the far-field transmitter 104 may be alight-emitting diode (LED), an edge-emitting diode laser, a line laserhaving an edge emitter and a (e.g., fiber) filter, or any other lightsource suitable for transmitting illumination signals to the far field.In some embodiments, after being shaped by the optical components of thefar-field transmitter 104, the emitted light signal 110 may be tightlyfocused (e.g., with divergence of less than 15 degrees, less than 10degrees, less than 5 degrees, less than 2 degrees, or less than 1degree), and may have a range of tens to hundreds of meters.

Collectively, the near-field transmitter 304, receiver 106, and control& data acquisition module 108 may be configured to operate as anear-field LiDAR device (e.g., channel), capable of providing data fromshort-range scan areas. In some applications, the near-field transmitter304 is structured and arranged to generate and emit a (e.g.,supplemental) laser (e.g., illumination) signal 310 that is capable ofilluminating objects 312 in a short-range scan area located within thenear field, such that the (e.g., short-range) return signals 314 may bereceived and detected by the receiver 106.

In some applications, the near-field transmitter 304 may be adapted toemit a short-range light (e.g., illumination) beam 310 to illuminateobjects in the near field. The short-range beam (sometimes referred toherein as a “flash beam”) may be significantly more diffuse and moredivergent than the long-range light beam 110, such that the short-rangebeam's energy density decreases rapidly with distance and effectiverange is low (e.g., a few meters). In some embodiments, the near-fieldtransmitter 304 includes one or more laser emitters each capable ofemitting a (e.g., short-range) laser beam. In some variations, each ofthe emitters of the transmitter 304 may be a vertical-cavitysurface-emitting lasers (VCSELs), a line laser having an edge emitterand a (e.g., fiber) filter, etc. In some embodiments, the short-rangetransmitter 304 may also include one or more diffusers adapted to shapethe beams generated by the short-range transmitter 304 such that theyfill the horizontal and vertical FOV of the LiDAR device 300.

Referring to FIG. 3B, a cross-sectional view of a portion of onepossible implementation of a hybrid LiDAR system 300 is shown. In theexample of FIG. 3B, the far-field transmitter 104 includes an emitter252, one or more optical components (e.g., lenses), and a movable mirror256. The movable mirror 256 may be configured to scan the long-rangebeam 110 generated by the emitter 252 over the horizontal FOV 332 (e.g.,120 degrees). In some embodiments, the LiDAR system 300 may include anarray of far-field transmitters 104 (e.g., 8, 16, 32, 64, or 128far-field transmitters), each of which may horizontally scan a differentportion of the system's vertical FOV (e.g., 32 degrees).

In the example of FIG. 3B, the far-field transmitter 104 is positionedbelow the near-field transmitter 304. In this example, the receiver 106is not shown, but shares at least a portion of the optical path of thetransmitter 104. Because the far-field emitter 252 is positionedrelatively close to the receiver 106 and to one or more opticalcomponents (which may reflect portions of an illumination beam emittedby the far-field emitter 252), the dazzle produced by the far-fieldemitter 252 at the receiver 106 can be very strong. In contrast, anydazzle produced by the near-field transmitter 304 at the receiver 106 ismuch weaker, for at least two reasons. First, the receiver 106 andnear-field transmitter 304 are located in separate, physicallypartitioned compartments, with baffles (342, 344) configured to limitoptical communication between the compartments. This physicalpartitioning and optical shielding limit the amount of dazzle that mightotherwise be produced by the emission of the line beam 310 from theshort-range transmitter 304. Second, even if a small amount of lightemitted by the short-range transmitter 304 reflects off the viewingwindow 330 of the LiDAR system 300 and is directed to the receiver 106,any dazzle produced by such internally reflected signals is relativelyweak because such internally reflected signals are not directly incidenton the receiver 106.

FIG. 3C shows a cross-sectional view of a near-field LiDAR transmitter304, in accordance with some embodiments. As discussed above, thenear-field transmitter 304 may include an emitter 352 and a diffuser306. The emitter 352 may be, for example, a VCSEL. The VCSEL may emit aline beam perpendicular to the substrate of the chip in which the VCSELis formed. In some embodiments, the beam emitted by the VCSEL issubstantially symmetric and exhibits substantial divergence (e.g., 20degrees by 20 degrees). In some embodiments, the VCSEL may emit a pulsedbeam, with a pulse repetition frequency of approximately 200 kHz. Otherpulse repetition frequencies (e.g., frequencies between 50 kHz and 500kHz) are possible. In some embodiments, the emitted line beam is shapedby a diffuser 306. The diffuser 306 may be any suitable diffractivebeam-shaping optical component. In some embodiments, the diffuserspreads the line beam 310 in the vertical and horizontal directions. Insome embodiments, the divergence of the diffused line beam 310 may matchthe FOV of the LiDAR device 300 (e.g., 120 degrees by 32 degrees).

In some embodiments, the LiDAR system 100 includes one secondtransmitter 304. In some embodiments, the LiDAR system 100 includes onesecond transmitter 304 per array of first transmitters 104 (or array offirst emitters) configured to scan different vertical regions of thesystem's FOV (e.g., array of 4, 8, 16, 32, or 64 transmitters oremitters). In some embodiments, the LiDAR system 100 includes one secondtransmitter 304 per first transmitter 104 (or emitter).

In some embodiments, the LiDAR system 100 activates a single receiver106 to receive return signals in the short-range listening period afterthe transmitter 304 emits a laser signal 310. In such embodiments, theLiDAR system 100 may be able to detect the presence of an object withinthe near field, but may not be able to determine the precise location ofthe object (e.g., the vertical and horizontal coordinates of the object)within the FOV. In some embodiments, the LiDAR system 100 activates twoor more receivers 106 (e.g., an array of 4, 8, 16, 32, or 64 receivers)to receive return signals in the short-range listening period after thetransmitter 304 emits a laser signal 310. In such embodiments, the LiDARsystem 100 may be able to detect the presence of an object within thenear field, and able to determine at least the vertical coordinate(s) ofthe object within the FOV. In some embodiments, the LiDAR system 100 mayactivate the second transmitter once each time the system finishesscanning the entire FOV, once each time a first transmitter (or firstemitter) finishes scanning a scan line (e.g., horizontal scan line)within the FOV, or once each time a first transmitter (or first emitter)scans a pixel within the FOV. Any of the foregoing configurations may besuitable for various applications of LiDAR system 100 (e.g., autonomousvehicle navigation).

Referring again to FIG. 3B, one of ordinary skill in the art willappreciate that the illustrated configuration of the near-fieldtransmitter 304 may not provide full coverage of the LiDAR system's FOVat a range of 2 meters or less, because the near-field transmitter 304is not positioned centrally with respect to the system's FOV. In someembodiments, the LiDAR system 300 may include a second near-fieldtransmitter 304, which may be positioned proximate to location 308.Together, the illustrated near-field transmitter 304 and a secondnear-field transmitter positioned proximate to location 308 may providefull coverage of the system's FOV. In some embodiments, the twonear-field transmitters may transmit pulses synchronously (e.g., withthe two transmitters transmitting their pulses simultaneously or in analternating sequence).

Advantageously, the timing of the firing of the transmitter 304 of thenear-field LiDAR device with respect to the firing of the transmitter104 of the far-field LiDAR device is selected, inter alia, to avoiddazzle interference. More particularly, the near-field transmitter 304may be adapted to generate and emit a flash (e.g., illumination) signal310 a predetermined amount of time before or after the generation andemission of light (e.g., illumination) signals 110 by the far-fieldtransmitter 104.

Preferably, the flash signal 310 is emitted separately and distinctlyfrom the (e.g., laser) light (e.g., illumination) signals 110 emitted bythe transmitter 104 of the (e.g. primary) LiDAR device 102. Suchemission may occur, for example, at the end of or at the beginning ofevery laser position (LPOS). Those of ordinary skill in the art canappreciate that the receiver 106 and control & data acquisition module108 integrated into the LiDAR device 102, as well as the data analysis &interpretation module 109, may also be used to control the firing of theflash signals 310 by the (e.g., supplemental) transmitter 304 of the(e.g., secondary) flash LiDAR device 302 and to receive and process thereturn flash signals 314. Optionally, in some embodiments, the (e.g.,secondary) flash LiDAR device 302 may be structured and arranged toinclude a separate receiver (not shown), control & data acquisitionmodule (not shown), and/or data analysis & interpretation module (notshown).

In embodiments, aspects of the techniques described herein (e.g., timingthe emission of the transmitted signal and the flash signal, processingreceived return signals, and so forth) may be directed to or implementedon information handling systems/computing systems. For purposes of thisdisclosure, a computing system may include any instrumentality oraggregate of instrumentalities operable to compute, calculate,determine, classify, process, transmit, receive, retrieve, originate,route, switch, store, display, communicate, manifest, detect, record,reproduce, handle, or utilize any form of information, intelligence, ordata for business, scientific, control, or other purposes. For example,a computing system may be a personal computer (e.g., laptop), tabletcomputer, phablet, personal digital assistant (PDA), smart phone, smartwatch, smart package, server (e.g., blade server or rack server), anetwork storage device, or any other suitable device and may vary insize, shape, performance, functionality, and price.

The computing system may include random access memory (RAM), one or moreprocessing resources such as a central processing unit (CPU) or hardwareor software control logic, ROM, and/or other types of memory. Additionalcomponents of the computing system may include one or more disk drives,one or more network ports for communicating with external devices aswell as various input and output (I/O) devices, such as a keyboard, amouse, a touchscreen, and/or a video display. The computing system mayalso include one or more buses operable to transmit communicationsbetween the various hardware components.

FIG. 4 depicts a simplified block diagram of a computingdevice/information handling system (or computing system) according toembodiments of the present disclosure. It will be understood that thefunctionalities shown for system 400 may operate to support variousembodiments of an information handling system—although it shall beunderstood that an information handling system may be differentlyconfigured and include different components.

As illustrated in FIG. 4, system 400 includes one or more centralprocessing units (CPU) 401 that provide(s) computing resources andcontrol(s) the computer. CPU 401 may be implemented with amicroprocessor or the like, and may also include one or more graphicsprocessing units (GPU) 417 and/or a floating point coprocessor formathematical computations. System 400 may also include a system memory402, which may be in the form of random-access memory (RAM), read-onlymemory (ROM), or both.

A number of controllers and peripheral devices may also be provided. Forexample, an input controller 403 represents an interface to variousinput device(s) 404, such as a keyboard, mouse, or stylus. There mayalso be a scanner controller 405, which communicates with a scanner 406.System 400 may also include a storage controller 407 for interfacingwith one or more storage devices 408 each of which includes a storagemedium such as magnetic tape or disk, or an optical medium that might beused to record programs of instructions for operating systems,utilities, and applications, which may include embodiments of programsthat implement various aspects of the techniques described herein.Storage device(s) 408 may also be used to store processed data or datato be processed in accordance with some embodiments. System 400 may alsoinclude a display controller 409 for providing an interface to a displaydevice 411, which may be a cathode ray tube (CRT), a thin filmtransistor (TFT) display, or other type of display. The computing system400 may also include an automotive signal controller 412 forcommunicating with an automotive system 413. A communications controller414 may interface with one or more communication devices 415, whichenables system 400 to connect to remote devices through any of a varietyof networks including the Internet, a cloud resource (e.g., an Ethernetcloud, an Fiber Channel over Ethernet (FCoE)/Data Center Bridging (DCB)cloud, etc.), a local area network (LAN), a wide area network (WAN), astorage area network (SAN), or through any suitable electromagneticcarrier signals including infrared signals.

In the illustrated system, all major system components may connect to abus 416, which may represent more than one physical bus. However,various system components may or may not be in physical proximity to oneanother. For example, input data and/or output data may be remotelytransmitted from one physical location to another. In addition, programsthat implement various aspects of some embodiments may be accessed froma remote location (e.g., a server) over a network. Such data and/orprograms may be conveyed through any of a variety of machine-readablemedium including, but are not limited to: magnetic media such as harddisks, floppy disks, and magnetic tape; optical media such as CD-ROMsand holographic devices; magneto-optical media; and hardware devicesthat are specially configured to store or to store and execute programcode, such as application specific integrated circuits (ASICs),programmable logic devices (PLDs), flash memory devices, and ROM and RAMdevices. Some embodiments may be encoded upon one or morenon-transitory, computer-readable media with instructions for one ormore processors or processing units to cause steps to be performed. Itshall be noted that the one or more non-transitory, computer-readablemedia shall include volatile and non-volatile memory. It shall also benoted that alternative implementations are possible, including ahardware implementation or a software/hardware implementation.Hardware-implemented functions may be realized using ASIC(s),programmable arrays, digital signal processing circuitry, or the like.Accordingly, the “means” terms in any claims are intended to cover bothsoftware and hardware implementations. Similarly, the term“computer-readable medium or media” as used herein includes softwareand/or hardware having a program of instructions embodied thereon, or acombination thereof. With these implementation alternatives in mind, itis to be understood that the figures and accompanying descriptionprovide the functional information one skilled in the art would requireto write program code (i.e., software) and/or to fabricate circuits(i.e., hardware) to perform the processing required.

It shall be noted that some embodiments may further relate to computerproducts with a non-transitory, tangible computer-readable medium thathas computer code thereon for performing various computer-implementedoperations. The medium and computer code may be those specially designedand constructed for the purposes of the techniques described herein, orthey may be of the kind known or available to those having skill in therelevant arts. Examples of tangible, computer-readable media include,but are not limited to: magnetic media such as hard disks, floppy disks,and magnetic tape; optical media such as CD-ROMs and holographicdevices; magneto-optical media; and hardware devices that are speciallyconfigured to store or to store and execute program code, such asapplication specific integrated circuits (ASICs), programmable logicdevices (PLDs), flash memory devices, and ROM and RAM devices. Examplesof computer code include machine code, such as produced by a compiler,and files containing higher level code that is executed by a computerusing an interpreter. Some embodiments may be implemented in whole or inpart as machine-executable instructions that may be in program modulesthat are executed by a processing device. Examples of program modulesinclude libraries, programs, routines, objects, components, and datastructures. In distributed computing environments, program modules maybe physically located in settings that are local, remote, or both.

One skilled in the art will recognize no computing system or programminglanguage is critical to the practice of the techniques described herein.One skilled in the art will also recognize that a number of the elementsdescribed above may be physically and/or functionally separated intosub-modules or combined together.

Method of Performing Short-Range Detection

Having described a hybrid LiDAR system 300 for compensating for dazzlein order to, inter alia, detect objects in the near field (e.g., within1 or 2 meters of the system 300, i.e., within a short-range scan areathat is spatially distant from the medium- and long-range scan areas),using a near-field transmitter 304 to match the FOV of the long-rangechannels, a method of detecting objects in a short-range scan areawithin the near field and mitigating the effects of dazzle will now bedescribed. Two variations of methods of mitigating the effects of dazzleand detecting objects in a short-range scan area within the near fieldwill now be described. The first technique involves one or morenear-field transmitters 304 transmitting flash line (e.g., illumination)beam(s) 310 towards objects 312 in a short-range scan area within thenear field prior to the time period corresponding to a laser position(LPOS) of the far-field transmitter 104, while the second techniqueinvolves a near-field transmitter(s) 304 transmitting flash line beam(s)310 towards objects 312 in a short-range scan area within the near fieldat the end of the LPOS of the far-field transmitter 104. In bothinstances, the timing of the firing of the flash line (e.g.,illumination) beam(s) 310 is controlled so that the short-range returnsresulting from the flash line (e.g., illumination) beam(s) 310 are notaffected by dazzle created by far-field transmitters 104.

Referring to FIG. 5 and FIGS. 6A and 6B, according to the firsttechnique, initially, the (e.g., medium- and long-range) transmitters104 and supplemental (i.e., short-range) transmitters 304 are in an OFFstate and the (e.g., long-range) channel detectors 106 in the LiDARdevice 102 are focused on the near field. As previously mentioned, thedetectors 106 may be integrated into each of the (e.g., primary) LiDARdevice 102 and the flash (e.g., secondary) LiDAR device 302; however, toreduce space and cost, for the purpose of this description, it will beassumed that the medium- and long-range channel detectors 106 areintegrated exclusively into the (e.g., primary) LiDAR device 102.

In a first embodiment of a method 500 for mitigating the effects ofdazzle, at time to, the supplemental (i.e., short-range) transmitters304 generate and emit (e.g., short-range) flash (e.g., illumination)signals 310 (act 510) towards objects 312 in a short-range scan areawithin the near field (e.g., between about 1 meter and 20 meters, or,more preferably, less than about 2 meters). The emitted flash signal 310illuminates the object(s) 312 in short-range scan area within the nearfield and is reflected back towards the system 300 as a return flashsignal 314 that, at time t₁, is received and detected (610, 615) by thechannel detectors 106 (act 520) integrated into the (e.g., primary)LiDAR device 102. Subsequently, the primary (e.g., long-range)transmitters 104 generate and emit a laser light (e.g., illumination)signal 110 (act 530). The latter laser light (e.g., illumination) signal110 causes, at time t₂, the detectors 106 integrated into the (e.g.,primary) LiDAR device 102 to receive and detect a signal correspondingto dazzle 620. Subsequently, second return signals 114 from objects 112in the medium- or long-range fields are received and detected 625 by thelong-range channel detectors 106 (act 540). Advantageously, the returnflash signals 314 are received and detected (610, 615) before theprimary (e.g., long-range) transmitters 104 produce dazzle 620 thatwould otherwise blind the (e.g., long-range) channel detectors 106 whileflash return signals 314 were reflected by (e.g., short-range)near-field objects 312. As a result, short-range, flash return data maybe received, detected, and processed within a short-range samplingperiod 600 extending approximately from a time just after the flashsignal 310 is emitted to a time just before the incidence of dazzle 620(or just before the emission of the long-range signal 110) (act 550).

Referring to FIG. 5 and FIGS. 7A and 7B, according to the secondtechnique (e.g., a second embodiment of the method 500 for mitigatingthe effects of dazzle), the primary (i.e., medium- and long-range)transmitter 104 generates and emits a light (e.g. illumination) signal110 (act 510) towards objects 112 in the medium- and long-rangeenvironment. The emitted light (e.g., illumination) signal 110illuminates objects 112 in the medium- and long-range environment and isreflected back towards the system 300 as return signals 114 that arereceived and detected 725 by the long-range channel detectors 106 (act520). After the last return signal 114 is received 725 by the long-rangechannel detectors 106, the supplemental (e.g., short-range) transmitter304 generates and emits a (e.g., short-range) flash light (e.g.,illumination) signal 310 (act 530) towards a short-range scan areawithin the near field. Subsequently, return flash signals 314 fromobjects 312 in the short-range scan area within the near fields arereceived and detected (710, 715) by the long-range channel detectors 106(act 540). Advantageously, the return flash signals 314 are received anddetected (710, 715) after the last return signal 114 produced by theprimary (e.g., medium- and long-range) transmitter 104 are received 725(see act 520), as well as after any dazzle 720 produced byback-reflecting resulting from the firing of the primary (e.g., medium-and long-range) transmitter 104. Advantageously, the return flashsignals 314 are received and detected (710, 715) after any dazzle thatwould otherwise blind the long-range channel detectors 106. As a result,(e.g., short-range) flash return data may be received, detect, andprocessed within a short-range sampling period 700 extendingapproximately from the end of the listening period for the medium- andlong-range returns (e.g., a period beginning when the primarytransmitter 104 emits the signal 110 and having a duration approximatelyequal to the round-trip travel time for a signal to reach an object atthe edge of the LiDAR system's long-range and for the reflected returnsignal 114 to travel back from that object to the LiDAR system) to theend of the listening period for the short-range returns (e.g., a periodbeginning when the secondary transmitter 304 emits the signal 310 andhaving a duration approximately equal to the round-trip travel time fora signal to reach an object at the edge of the LiDAR system'sshort-range and for the reflected return signal 314 to travel back fromthat object to the LiDAR system).

It will be appreciated to those skilled in the art that the precedingexamples and embodiments are exemplary and not limiting to the scope ofthe present disclosure. It is intended that all permutations,enhancements, equivalents, combinations, and improvements thereto thatare apparent to those skilled in the art upon a reading of thespecification and a study of the drawings are included within the truespirit and scope of the present disclosure. It shall also be noted thatelements of any claims may be arranged differently including havingmultiple dependencies, configurations, and combinations.

What is claimed is:
 1. A light detection and ranging (LiDAR) methodcomprising: generating, by a first transmitter, a first lightillumination signal; generating, by a second transmitter, a second lightillumination signal; receiving first return signals corresponding to thefirst light illumination signal; receiving second return signalscorresponding to the second light illumination signal; and sampling thefirst return signals or the second return signals during a short-rangesampling period, such that the short-range sampling period avoids aperiod of dazzle.
 2. The method of claim 1, wherein the firsttransmitter generates a first light illumination signal having a longerrange that the second light signal.
 3. The method of claim 2, whereinthe second light illumination signal has a range between about 10 metersand about 20 meters.
 4. The method of claim 2, wherein the second lightillumination signal has a range of less than about 2 meters.
 5. Themethod of claim 2, wherein the second light illumination signal has arange between about 1 meter and about 20 meters.
 6. The method of claim1, wherein the first light illumination signal is emitted before thesecond light illumination signal.
 7. The method of claim 1, wherein thesecond light illumination signal is emitted before the first lightillumination signal.
 8. The method of claim 1, wherein generating afirst light illumination signal comprises emitting a light illuminationsignal towards a medium-range scan area and/or a long-range scan area.9. The method of claim 8, wherein generating a second light illuminationsignal comprises emitting a light illumination signal towards ashort-range scan area.
 10. The method of claim 9, wherein theshort-range scan area is spatially distant from the medium-range scanarea and/or the long-range scan area.
 11. The method of claim 1, whereingenerating a first light illumination signal comprises emitting a lightillumination signal towards a short-range scan area.
 12. The method ofclaim 11, wherein generating a second light illumination signalcomprises emitting a light illumination signal towards a medium-rangescan area and/or a long-range scan area.
 13. The method of claim 12,wherein the short-range scan area is spatially distant from themedium-range scan area and/or the long-range scan area.
 14. The methodof claim 1, wherein the short-range sampling period occurs before thedazzle signal is received.
 15. The method of claim 1, wherein theshort-range sampling period occurs after a last return of the firstreturn signals.
 16. The method of claim 1, wherein the first lightillumination signal is generated and the first return signals arereceived prior to generating the second light illumination signal. 17.The method of claim 1, wherein each of the first return signal and thesecond return signal is received by a common channel signal detector.18. The method of claim 1 further comprising diffusing, using adiffuser, the first light signal or the second light signal.
 19. A lightdetection and ranging (LiDAR) system comprising: a first transmitteradapted to generate and emit a first light illumination signal towardsat least one of a medium-range scan area or a long-range scan area; areceiver adapted to detect and receive first return signalscorresponding to the first light illumination signal; and a secondtransmitter adapted to generate and emit a second light illuminationsignal towards at least one object in short-range scan area within anear field, wherein the receiver is further adapted to receive secondreturn signals corresponding to the second light illumination signal.20. The system of claim 19, wherein the short-range scan area isspatially distant from at least one of the medium-range scan area or thelong-range scan area.
 21. The system of claim 19 further comprising acontrol and data acquisition module.
 22. The system of claim 21, whereinthe control and data acquisition module is structured and arranged tocontrol the first transmitter, the receiver, and the second transmitter.23. The system of claim 19 further comprising a data analysis andinterpretation module structured and arranged to process data receivedfrom the receiver.
 24. The system of claim 19, wherein the secondtransmitter comprises at least one vertical-cavity surface-emittinglaser (VCSEL).
 25. The system of claim 19, wherein the range of thesecond light illumination signal is between about 10 meters and about 20meters.
 26. The system of claim 19, wherein the range of second lightillumination signal is less than about 2 meters.
 27. The system of claim19, wherein the range of the second light illumination signal is betweenabout 1 meter and about 20 meters.
 28. The system of claim 19 furthercomprising a diffuser disposed between the second transmitter and atleast one object.
 29. The system of claim 19, wherein the secondtransmitter comprises a baffle configured to reduce transmission oflight from the second transmitter to the receiver along an optical pathinternal to the LiDAR system.